Church budgeting doesn't need to be complicated to be effective — it needs to be honest and reviewed regularly. Start with three broad categories: staff and operations (the recurring costs of simply running each week), ministry and programs (what you spend to actually do the mission), and missions/outreach (what goes beyond your own walls).
A common rule of thumb many churches use as a starting point is roughly 50% to staffing, 30% to operations and facilities, and the remaining split between ministry programs and outreach — though this varies significantly by size and context, and shouldn't be treated as a rigid rule.
Track actual giving against budget monthly, not just at year end. A shortfall caught in March is a small adjustment; the same shortfall discovered in November is a crisis.
Whatever your size, keep giving records separate from bookkeeping opinions — every donation should be tied to a specific fund and donor record automatically, so that financial reporting is a matter of pulling a report, not reconstructing memory.